Change Video Resolution: 1080p, 720p and Multi-Platform Outputs
Resolution is pixel count. The only safe direction is down — upscaling blur is arithmetic, not a tool flaw.
Down only: the safe direction
1080p to 720p discards pixels the picture never needed — visually near-lossless. The reverse invents pixels the source lacks, and softness follows.
So derive multi-platform versions from the highest-resolution master downward. Keep the master untouched; never use a compressed derivative as the source.
Equal-ratio scaling and algorithms
Setting height auto-computes width, so nothing distorts. Height presets run 480/720/1080/1440 — for vertical video the height is the long edge.
The algorithm decides how pixels are dropped: lanczos preserves the most detail for final exports; bicubic balances speed and quality; bilinear is fastest for previews. Default to lanczos when quality matters.
Resolution changes always re-encode
New resolution means new pixel data — there is no "resize without re-encode" shortcut. Bitrate must follow the resolution down, or the file barely shrinks.
If the goal is smaller size at the same resolution, plain compression is the right tool. Resolution changes fit "platform only accepts 720p", "free up phone storage", or "low-spec device versions".